1985 Pete 359

Theres no tolerable amount of bubbles .. if its got bubbles its got issues
250° is enough to do damage especially on a hard pull.. I would bet the head is cracked .. just like @wore out said between the #5 & #6 ..
If theres bubbles theres a issue
If you can post some picture that would be great .. I'am not saying Iam not interested

 

Like a cabover. Cool to look at and that's about it.
And as previously mentioned, pics would help a lot.

 

Idle the truck it needs to run through 2 cycles of the fan kickin on and off from temp by itself out the bottle on it if no bubbles at idle the rev up and hold still none your good. Any at idle or high idle indicates a problem. Another thing I do is make sure it’s full and put my pump up coolant tester on it. No pressure but flip it to lock like I’m gonna pressure test it. Start it from cold let it run 45 minutes to an hour anything over 10-12 you have issues.


I will also say at 250 the odds of a cracked head are high. But see the head doesn’t crack from heat but pressure. If the coolant mixture was right and it was full with a 7 lbs cap you’re probably ok. As the coolant gets warmer the higher water concentration it has the sooner in turns to steam. Being under pressure of the 7 lbs cap raises that number as well but the steam pressure for lack of a better word pushing outward cracks the head. The head alone is 3500 with a core 3200 aftermarket no core. But at 250 that ain’t your main concern its the o-rings on bottom of the liner. They get soft at that temp and a leak is coming. A Pete guage maxes out at 250…..that doesn’t mean the motor temp did. Again I’m not picking on it I’m sure it’s a neat ol truck. but like all neat ol trucks mine included some work required